4344 Mk II network

[4313B]

System information. Pages 3, 4 and 5 are blank.

[4313B]

Schematic

[4313B]

L3 & R8

3.5 mH (1.0 ohm DCR) & 6.2 ohm

L6 & R13

1.0 mH (0.4 ohm DCR) & 7.5 ohm

These traps function exactly the same way as they did in the legacy L110, L212 and various other JBL loudspeaker systems. Back then the inductors were nice little cubes with the ~ 7.5 ohm DCR built right in. :)

Below is how L3 & R8 affect the 2122H and 2123H in the ubiquitous 0.5 cubic foot subenclosure JBL has used in the 43xx Series monitors.

[spirou38]

L3 & R8

3.5 mH (1.0 ohm DCR) & 6.2 ohm

L6 & R13

1.0 mH (0.4 ohm DCR) & 7.5 ohm

These traps function exactly the same way as they did in the legacy L110, L212 and various other JBL loudspeaker systems. Back then the inductors were nice little cubes with the ~ 7.5 ohm DCR built right in. :)

Below is how L3 & R8 affect the 2122H and 2123H in the ubiquitous 0.5 cubic foot subenclosure JBL has used in the 43xx Series monitors.

Hi 4313B,

Great ! :applaud:
Thank you very much.
Where did you got those informations from ?

Best regards from France.

Pascal

[Ian Mackenzie]

It worth pointing out the above schematic (rev 4 ?)was probably redrawn after the Technical Manual Schematic (Rev 2 8/?) which had some errors.

Its fairly obvious so and not trivial.

[4313B]

Comparison of 2405 voltage drives in various JBL Studio Monitors:

The 0.16 mH tapped autotransformer used in the 4344/4345 and 4355 is the same core with three taps. In the 4344/4345 the taps are wired so that there is an ~ 8 dB drop. In the 4355 the taps are wired to that there is an ~ 4 dB drop.

One example unit:
Primary tap 0.158 mH
Secondary tap can be either 0.026 mH ( - 8 dB ) or 0.067 mH ( - 4 dB ) depending on wiring. The actual matrix worked out by David Smith is shown below. In any case, Greg no longer uses them and prefers non-inductive fix resistor solutions as per the 4344 Mk II.

[phamphare]

Absolutely fantastic !
Never seen such a perfect work.

And thank you for the documentation because I am beginning to follow the same lane.
For the time I collect spare parts.

I came to, precisely, this model 4345 because I had, long years ago, a new pair of 3 ways 432x with LE15A, 375 and 077 or their professionnal equivalent I don't remember.
I found that 4345 were better because of the fourth way in the medium.
But I neglected to upgrade my JBL for WAF reasons.

I search for the exact design of the cabinet. Could you tell me where to find it?

[spirou38]

I search for the exact design of the cabinet. Could you tell me where to find it?

Here it is :

http://www.audioheritage.org/vbulletin/showthread.php?t=11856

[Jakob]

It worth pointing out the above schematic (rev 4 ?)was probably redrawn after the Technical Manual Schematic (Rev 2 8/?) which had some errors.

Its fairly obvious so and not trivial.

I'm in the process of collecting drivers for these speakers. Regarding the crossovers, is the network above the correct one. Ians post got me thinkin...

[Jakob]

Regarding inductor DCR: in the specifications it says f.e. "<0.6ohm". Should I try to get as close as possible to the stated value, or is any value below the stated OK?